It more particularly concerns methods of detecting the presence of a lubricant sprayed onto the surface of a component designed to slide inside another component.
When it is necessary to apply a small quantity of lubricant to a surface of difficult access and/or of small size, for example between two components of small size, it is preferably applied by spraying it in order to control its application.
Now it is important, when a lubricant is applied to a surface by spraying it, to be sure that the lubricant has indeed reached the zone, termed the target zone, of that surface to which it is required to apply the lubricant.
In fact, because of its application by spraying, the lubricant may not reach the target zone. This can happen if spraying is effected at too great a distance from the target zone or if the spraying means are obstructed.
In some circumstances it can also happen that it is only detected at a very late stage that the lubricant has not been applied correctly to the target zone, notably when the target zone is part of an assembly necessitating a plurality of assembly steps. This detection can nevertheless be achieved by visual inspection by an operative. However, visual inspection represents a non-negligible cost and necessitates the operative being close to the target zone, which is not always feasible in an automated environment.
For example, if the lubricant is applied in the context of the assembly of a device such as a metering valve for dispensing a pharmaceutical product, it can happen that it is not noticed that the lubricant has not been applied to the target zone before the final phases of testing the fully assembled device. This leads to rejecting the device very late in the process of manufacturing the device, generating loss of time and profit.